HEPARAN-SULFATE IN THE STONE MATRIX AND ITS INHIBITORY EFFECT ON CALCIUM-OXALATE CRYSTALLIZATION

The nature of the soluble stone matrix and its possible role in urinar y stone formation was studied. For this purpose we performed two-dimen sional cellulose acetate membrane electrophoresis of the glycosaminogl ycans (GAGs) which were contained in the soluble stone matrix, substan ces adsorbed onto calcium oxalate crystals in vitro (crystal surface b inding substances, CSBS) and urinary macromolecules (UMMs). The main G AG in the soluble stone matrix and CSBS was found to be heparan sulfat e, whereas the UMMs contained various GAGs usually seen in urine. An i nhibition assay showed the soluble stone matrix to have the strongest inhibitory activity among these macromolecular substances when inhibit ory activity was expressed in terms of uronic acid concentration. It i s suggested that the main GAG in the soluble stone matrix consists of heparan sulfate, which has a strong inhibitory activity on calcium oxa late crystal growth and aggregation and constitutes part of the CSBS.